Technical Stuff

The following is a list of things that may help. It is in no particular order.

Reset Circuit

The Midway Service Note #2 identifies a problem with the reset circuitry. Resets on the logic board are done two ways. One is a simple power-on-reset used to ensure the game starts properly. The second is a internally triggered reset to do an automatic reset on certain conditions (like pushing the "Game" button on the keyboard). The revised reset circuit Midway describes is on the power-on-reset.

I feel a better way of doing the power-on-reset is to clip and remove pin 2 of chip A2-3 (LM339) as shown above and solder in a DS1811 or MCP130 to the underside of the logic board to control reset as shown to the left. Lead 1 to pads 1-2 of A2, lead 2 to the +5 volt rail, and lead 3 to pad 12 (ground) of A2. This results in a clean 150 ms reset pulse on power-up with no coil chatter as often found on the original reset circuit.

Power Supply

It is very good practice to replace the 11,000 ufd filter capacitor on the power supply board. I was getting intermittent failures of supply voltage to a game that was traced back to this capacitor. Value is not critical as long as it is adequate (8000 ufd or more with at least a 16 volt rating).

Re-Pinning

It is a very good idea to re-pin at least the contacts on J0 and J1 which feed power to the logic board. For those connectors, I used the trifulcon series contacts to ensure a good connection.

Errata

I found a few errors in both the E627 and G627 schematics.

E3 (74ls174) - pin 13 is connected to AD5, not AD4, pin 11 is connected to AD4, not AD3

Reset line from pin 17 of K3-4 (0066-177XX) is connected to pin 15 of all 74ls259s, not just D5.

Substitute Parts

The NPN Darlington pair transistor (RCA D42D1) used in the Rows matrix driver appears to be not available anywhere. I found a TIP102 is a drop in replacement. The PNP Darlington pair transistor (RCA D45E1) used in the Column matrix is also not available and can be replaced with a TIP107.

The audio amp chip used on the G series logic board (LM377) is difficult to source. The later version LM1877 chip is pin-for-pin compatible and works well. Don't forget to replace the original heat sink or epoxy a replacement to it's back.

The audio generator (0066-117XX) is a rare custom chip. In addition to Rotation VIII, it was also used in Gorf, Wizard of Wor, Space Zap, Extra Bases, Sea Wolf II and perhaps others. It was also used in the Astrocade game console.

The pop bumper tops are the same used by the Bally Eight Ball (not Deluxe)

First Time Power-Up

To get started, here is what I suggest: (this is not necessary, but it makes access a lot easier, disconnect the 15 pin Molex connector by the one coin door and lift the frame out of the cabinet. A couple of short 2/4s over the top of the cabinet allows you to sit the frame on top and still reconnect the 15 pin Molex connector.) See below. This is a good time to check the power cable too.

1) Do a visual inspection of the underside of the playfield to look for shorted wires and open connections. Check for any discoloured coils which may have heated.
2) Install the PCBs and connect all the connectors.
3) Power up the game. If any coils immediately fire or if random lights (not just the rack) come on, turn off the power and trouble shoot the logic board. If the logic board works, you should get a short tune, the display goes to all zeros, then alternates between 0 and 400000 and the balls on the rack sequentially illuminate. If the rack balls light sequentially, but no tune, you may have a bad speaker which is pretty common. A thumbwheel pot on the left side of the logic board controls volume.
4) On the keypad, push "end" then push test 1. All bulbs should continue to flash quickly. You can see if any bulbs are out.
5) On the keypad, push "end" then push test 2. The switch closures should show on the display. The electrical manual provides details on numbers. With the ball removed from the outhole, you should see something around 07 or so, depending on the position of the shaft encoder. You can sequentially go through and close the switch contacts while watching the display.
6) On the keypad, push "end" then test 3. The coils should fire sequentially, except for the flippers. You can make the flippers fire also by holding down the flipper buttons, but it also will depend on playfield positioning as to which buttons to push. Push "end" to end the test.
7) On the keypad, push "end" then test 5. The displays should all count up starting at 0.
8) Once you have successfully done tests 1-3 and 5, go to my calibration page for calibrating the playfield.

Troubleshooting (Electronic)

First, check power voltages. I've found a slightly low logic supply of 4.85-4.90 volts typical. A supply of less than 4.5 v will cause problems. The original Characterization board also uses -5 volts, +12 Volts and +9 volts.

For a non-booting machine, put a scope or logic probe on pin 2 of J-8 (an unused logic board connector). That is the reset line. If there are continuous resets, the board is not properly loading the software. Time to look at the Characterization board (if it is the original) the controller (8156), or bus drivers (81LS95 and 8304). A non-booting board without continious resets may indicate a missing clock signal or a bad counter (A-1).

Troubleshooting (Mechanical)

On a booting machine (in attract mode) access the keypad and press Test #4. The encoder should display it's position as shown on the Calibration page. Press "End", then Test #6 and on manual rotation of the playfield you should see the display pass from 0 to 1 to 3 to 2 when at each compass direction (or backwards depending on rotation). If you are not getting these displays, there is a problem with related circuitry. Missing or inorrect signals from the shaft encoder (Test #4) or the optical sensor (Test #6) can result from cold solder joints on the encoder board, or on the optical sensor board. If all the displays are ok, review my Calibration page. Remember that the ball must be in the outhole for the table to rotate.

If the playfield oscillates and can't settle to position, there may be loose hardware in the drive mechanism or on the base where the main spindle bolts to the base.

Access

The General Instructions manual provides details on game assembly. Easy access to all the boards can be gained by disconnecting the Molex connector near the tilt switch and lifting the entire unit out of the case. A couple of 2x4s across the top of the case can then support the frame while allowing re-attachment of the Molex connector.